I've been having quite a struggle with a '54 Ford project I've been helping with. The engine was rebuilt and has just 200-300 miles, the distributor is rebuilt and has only a few miles on it, the carb was rebuilt and has even fewer miles. Plugs, points, cap, rotor, wires, everything... new. (and set correctly)

The engine starts easy and idles nicely. If you run it ***** out, it functions pretty well, but if you drive it normally it sputters, chugs, misses, and doesn't have near the power it should. I have 17 in. manifold vacuum at idle. I have 0 in. vacuum at the vacuum advance at idle. When driving, the vacuum at the vacuum advance never goes over 3 in.

I've about run out of ideas, but it seems like the vacuum for the advance should run higher than 3 during normal driving. That brings me to the carburetor question. Could it be the spark control valve in the carburetor is not allowing enough vacuum to the vacuum advance? Could that be what's causing all my problems at low speed, low throttle?